Class T and Class SM coupling for sucker rods are manufactured as per API Specification 11B. For the thread cutting, we are using cold form rolled by displacing rather than by removing of material for making the coupling thread. The thread rolling cutting results in a compressive stress at the root of the thread, giving maximum strength to the traditional weak point of cut-thread couplings.
Class T coupling is using AISI 5140 to manufacture.The coupling is coated using phosphate chemical treatment or black oxide on customer's request.For Class SM coupling, the spray metal is a specification hardening process and is applied on the base metal.
The couplings are available in full size, slim hole and over size.Also, combination couplings are available for different diameters (sub-coupling) for both Class T and Class SM couplings.
We recommend changing sucker rod couplings after three make-ups, provided the connection threads have been inspected and deemed acceptable for reuse.